In treating toilet flush water with chemicals so as to produce desirable effects such as bowl aesthetics, cleaning, disinfection, deodorization, etc., it is desirable that the chemicals be dispensed into the flush water automatically each time the toilet is flushed. The prior art discloses numerous solid lavatory cleansing blocks which have the capability of automatically dispensing metered amounts of chemicals to effect cleaning and sanitizing. However, prior to the present invention the oxidizing lavatory blocks or tablets had the disadvantage of a short shelf life and block life during use.
U.S. Pat. No. 4,780,236 to Bunczk, et al., issued Oct. 25, 1988, which is herein incorporated by reference, discloses a lavatory cleansing block containing polyethylene glycol distearate, guar gum, and sodium chloride. This patent, particularly in columns 3 through 5, identifies a variety of compositions and their concentrations for use in manufacturing a lavatory cleansing block or "toilet cake".
U.S. Pat. No. 3,504,384, Radlevy et al, which is herein incorporated by reference discloses a dual compartment dispenser for automatically dispensing a hypochlorite solution and a surfactant/dye solution to the toilet bowl during flushing. The dye which is taught in the patent is Disulfide Blue VN150. This dye is resistant to oxidation to a colorless state by hypochlorite; thus, it provides a persistent color to the toilet bowl water, even in the presence of the hypochlorite.
U.S. Pat. No. 4,269,723 to Barford, et al., which is herein incorporated by reference, discloses a process for making lavatory cleansing blocks by tabletting a free flowing particulate mix consisting essentially of, on a weight basis, from 5 to 90% of a surface active component and from 0.5 to 75% of one or more binders selected from clays and water soluble or water dispersible gel forming organic polymeric materials. Of the water soluble polymeric binders various optional components are also mentioned by Barford; namely, dyestuffs, perfume, water soluble fillers, water softening or chelating agents, solid water soluble acids, inert water insoluble inorganic or organic fillers, tablet lubricants, and agents having disinfecting or germicidal activity. Lubricants have been found to be ineffective to provide any effect of preventing degradation because of the presence of oxidizing agents.
U.S. Pat. No. 4,460,490 to Barford, et al., which is herein incorporated by reference discloses a freestanding lavatory cleansing block that comprises a shaped body formed of a slow dissolving cleansing composition containing a surface active agent and a tablet comprising a bleaching agent embedded in or adhered to the shaped body. The shaped body, according to the '490 patent, may be melt cast, tabletted, or extruded, depending upon the geometry of the shaped body. The shaped body preferably comprises the aforesaid surface active agent and a solubility control agent, for example, a water soluble or water dispersible gel forming polymer, for example, chemically modified celluloses.
U.S. Pat. No. 4,043,931 to Jeffrey, et al., which is herein incorporated by reference, discloses a lavatory cleansing block comprising a solid carrier base which is a mixture of two or more nonionic surface active agents, one of which is relatively insoluble in water and the other of which is relatively soluble in water. Suitable relatively water insoluble nonionic surface active agents are the mono and dialkanolamides of long chain fatty acids and polyalkoxylated fatty alcohols containing up to 6 moles of alkoxide. Suitable relatively water soluble surface active agents include polyalkoxylated fatty alcohols of more than 6 alkyleneoxy units per molecule and the alkyleneoxy block copolymers. The lavatory block of Jeffrey may optionally include perfume, dyestuff, germicide, and fillers, the latter being for example, a water softener such as a alkali metal polyphosphate. The blocks of Jeffrey are made by tabletting.
U.S. Pat. No. 4,229,410 to Kosti, which is herein incorporated by reference, discloses a bacteriostatic toilet element comprising a water sensitive, water soluble or swellable binding agent and a bacteriostatic and/or deodorizing and/or coloring agent. Kosti's element may be melt cast or extruded.
U.S. Pat. No. 4,119,578 to Daeninck, et al., discloses a hydrosoluble bar obtained by extrusion, the bar containing paraffin sulfonate as an extrusion aid.